# CVE-2021-20091: Command injection in Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3

> An authenticated attacker can inject commands via the web interface to alter configuration and execute arbitrary code on Buffalo routers.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-6rqh-8mhj-w4pr

## What is CVE-2021-20091?

CVE-2021-20091 is a high-severity command injection vulnerability in Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3, published on 29 Apr 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 do not properly sanitize user input. An authenticated remote attacker could leverage this vulnerability to alter device configuration, potentially gaining remote code execution.

## Which versions are affected by CVE-2021-20091?

It affects 2 products.


Products: Buffalo Wsr-2533dhp3-Bk Firmware, Buffalo Wsr-2533dhpl2-Bk Firmware.

## How do I fix CVE-2021-20091?

No fix has been published for CVE-2021-20091 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20091 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-20091 exists.

Public exploit code:

- Buffalo WSR-2533DHPL2 - Configuration File Injection (nuclei): http/cves/2021/CVE-2021-20091.yaml

## Other vulnerabilities in Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3

- [CVE-2021-20090](https://insights.sbomify.com/CVE-2021-20090/): Arcadyan Buffalo Firmware Path Traversal (critical 9.8, exploited in the wild)
- [CVE-2021-20092](https://insights.sbomify.com/CVE-2021-20092/): Information disclosure in Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3 (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20091 and fix it if it is affected.

What it is: CVE-2021-20091 is a high-severity command injection vulnerability in Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3, published on 29 Apr 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-20091 exists.

Affected product: Buffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-20091/ (Markdown: https://insights.sbomify.com/CVE-2021-20091/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20091
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20091
- OSV: https://osv.dev/vulnerability/CVE-2021-20091

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-20091/
Summaries are generated and may contain mistakes; the official description above is the record.